Flood Potential Outlook
Issued by NWS Bismarck, ND

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 
000
FGUS73 KBIS 261546
ESFBIS
NDC001-007-011-015-021-025-029-031-033-037-041-043-045-047-051-
053-055-057-059-065-083-085-087-089-093-103-105-301800-

PROBABILISTIC HYDROLOGIC OUTLOOK
NATIONAL WEATHER SERVICE BISMARCK ND
0905 AM CDT FRI APR 26 2013


...FLOOD AND WATER RESOURCES OUTLOOK...

THIS PROBABILISTIC FLOOD OUTLOOK IS FOR THE MISSOURI AND JAMES RIVER
BASINS OF WESTERN AND CENTRAL NORTH DAKOTA...COVERING THE TIME PERIOD
OF LATE APRIL THROUGH LATE JULY.

THE FOLLOWING MESSAGE HAS THREE SECTIONS...THE FIRST PROVIDES SOME
TEXT ON HIGHLIGHTS OF THIS PRODUCT AND CONDITIONS AFFECTING LOCAL
HYDROLOGY. THE SECOND GIVES THE CURRENT AND NORMAL/HISTORICAL
CHANCES OF RIVER LOCATIONS REACHING THEIR MINOR...MODERATE...AND
MAJOR FLOOD CATEGORY. THE FINAL SECTION GIVES THE CURRENT CHANCES
OF RIVER LOCATIONS RISING ABOVE LISTED RIVER STAGES.


...FLOOD OUTLOOK OVERVIEW HIGHLIGHTS...
THIS OUTLOOK CONTAINS UPDATED PROBABILISTIC TABLES FOR THE RISKS
ASSOCIATED WITH REACHING THE DEFINED FLOOD STAGES. THIS SPRING HAS
BEEN COOLER THAN NORMAL ACROSS THE ENTIRE AREA AND RESULTED IN SNOW
RETENTION WELL INTO APRIL FOR LARGE PARTS OF THE JAMES RIVER BASIN
ALONG WITH THE EASTERN AND NORTHERN PARTS OF THE MISSOURI WATERSHED.
THE RISKS ASSOCIATED WITH FLOODING DUE TO THE REMAINING SNOWPACK ARE
ACTUALLY NOT CONTAINED WITHIN THIS FLOOD OUTLOOK AS THE SNOW IS
EXPECTED TO MELT AND BE LARGELY BE GONE BY 30 APRIL..THE EFFECTIVE
DATE OF THIS OUTLOOK.

THE EFFECT OF THE AFOREMENTIONED SNOW THOUGH IS CAPTURED IN THE
MODELS THROUGH AN INCREASE IN SOIL MOISTURE FOR THE BEGINNING OF
THIS OUTLOOK. EVEN WITH A FAIRLY ROBUST WETTING OF THE UPPER SOILS
FROM THE RECENT...AND ONGOING SNOW MELT...THE OVERALL RISK OF
FLOODING STILL IS LOWER THAN THE HISTORICAL MODEL. THIS SUGGESTS A
SLIGHTLY LESS THAN NORMAL RISK OF RIVER FLOODING AS WE GO INTO LATE
SPRING AND EARLY SUMEMR.

...CURRENT CONDITIONS...
RIVERS AND STREAMS ACROSS THE AREA ARE A MIXTURE OF ICE COVERED AND
CURRENTLY FREE FLOWING. THIS WILL CHANGE OVER THE NEXT FEW DAYS WITH
LITTLE TO NO ICE REMAINING ON THE RIVERS AND STREAMS BY EARLY MAY.
AS MOST OF THE SNOWMELT RUNOFF HAS BEEN INFILTRATED INTO THE
SOIL...THIS HAS KEPT THE RIVER LEVELS WELL BELOW FLOOD STAGE SO FAR
THIS SPRING.


...WEATHER OUTLOOK...
THE GENERAL TREND IS FOR THE COOLER THAN NORMAL TEMPERATURE PATTERN
TO REMAIN IN PLACE FOR THE MONTH OF MAY AND THEN TRANSITION INTO AN
EQUAL CHANCE FOR A BELOW NORMAL...NORMAL...OR ABOVE NORMAL PATTERN.
A SLIGHTLY HIGHER THAN NORMAL PROBABILITY FOR ABOVE NORMAL
PRECIPITATION DISSIPATES IN EARLY MAY LEAVING THE AREA WITH AN EQUAL
CHANCE FOR ABOVE NORMAL TO BELOW NORMAL PRECIPITATION.

...SUMMARY OF HYDROLOGIC CONDITIONS...
GIVEN THE LATE SPRING MELT AND MELTING SNOW...SOIL MOISTURE
CONDITIONS ARE EXPECTED TO GREATLY IMPROVE ACROSS THE JAMES AND
NORTHERN PORTIONS OF THE MISSOURI RIVER BASIN IN NORTH DAKOTA. RIVER
LEVELS NOT UNDER THE INFLUENCE OF SIGNIFICANT SNOWMELT AT THIS POINT
ARE GENERALLY IN THE RANGE OF NORMAL.


...LONG-RANGE PROBABILISTIC RIVER OUTLOOK BY FLOOD CATEGORY...
THE TABLE BELOW GIVES BOTH THE CURRENT CHANCES (CS) AND THE
NORMAL/HISTORICAL CHANCES (HS) FOR EXCEEDING THE MINOR...MODERATE
AND MAJOR FLOOD STAGES AT THE RIVER FORECAST POINT LOCATIONS DURING
THE VALID PERIOD OF THIS OUTLOOK.



                    JAMES AND MISSOURI RIVER BASINS
                    LONG-RANGE PROBABILISTIC OUTLOOK

        PROBABILITIES FOR MINOR...MODERATE AND MAJOR FLOODING
                    FROM  4/30/2013 TO 7/29/2013 Z

TABLE 1                                  : CURRENT AND HISTORICAL
                                         : CHANCES OF EXCEEDING FLOOD
                                         : CATEGORY IN PERCENT (%)
                         CATEGORICAL     :
                      FLOOD STAGES (FT)  :  MINOR   MODERATE  MAJOR
LOCATION            MINOR    MOD   MAJOR :  CS HS    CS HS    CS HS
--------            ------ ------ ------ : --- ---  --- ---  --- ---
LITTLE MUDDY CREEK.....
  WILLISTON           10.0   12.0   14.0 :  30  36   22  25    5  <5
LITTLE MISSOURI RIVER.....
  MARMARTH            18.0   23.0   30.0 :  <5   5   <5  <5   <5  <5
  MEDORA              15.0   18.0   20.0 :  <5   7   <5   6   <5   5
  WATFORD CITY        20.0   24.0   30.0 :  <5  <5   <5  <5   <5  <5
KNIFE RIVER.....
  MANNING             15.0   17.0   20.0 :   9  13   <5  <5   <5  <5
SPRING CREEK.....
  ZAP                 14.0   18.0   20.0 :  15  22   10   9   <5  <5
KNIFE RIVER.....
  HAZEN               21.0   24.0   25.0 :   5  18   <5   6   <5  <5
HEART RIVER.....
  MANDAN              17.0   23.0   28.0 :   5   7   <5  <5   <5  <5
APPLE CREEK.....
  MENOKEN             15.0   16.0   17.0 :  39  51   31  40   16  21
CANNONBALL RIVER.....
  REGENT              22.0   24.0   26.0 :  <5  <5   <5  <5   <5  <5
CEDAR CREEK.....
  RALEIGH             12.0   14.0   16.0 :  <5  <5   <5  <5   <5  <5
CANNONBALL RIVER.....
  BREIEN              10.0   20.0   23.0 :   6  22   <5  <5   <5  <5
BEAVER CREEK.....
  LINTON               9.0   11.0   13.0 :  33  38   26  32   11  23
JAMES RIVER.....
  GRACE CITY          12.0   14.0   15.0 :  <5  <5   <5  <5   <5  <5
PIPESTEM CREEK.....
  PINGREE              9.0   11.0   13.0 :   6  14   <5  <5   <5  <5
JAMES RIVER.....
  LAMOURE             14.0   16.0   18.0 :  11   7    9  <5   <5  <5

LEGEND:
    CS  =  CONDITIONAL SIMULATION (OUTLOOK FOR CURRENT CONDITIONS)
    HS  =  HISTORICAL SIMULATION  ( "       "  NORMAL  CONDITIONS)
    FT  =  FEET ABOVE GAGE ZERO DATUM


...LONG-RANGE PROBABILISTIC OUTLOOK BY RIVER STAGE...


THE TABLE BELOW GIVES THE CURRENT 95 THROUGH 5 PERCENT CHANCES FOR
EXCEEDING RIVER STAGES AT THE RIVER FORECAST POINT LOCATIONS DURING
THE VALID PERIOD OF THIS OUTLOOK.

EXAMPLE: DURING THE VALID TIME OF THIS OUTLOOK...THERE IS A
         50 PERCENT CHANCE FOR THE LITTLE MUDDY CREEK AT
         WILLISTON TO RISE ABOVE 5.0 FEET AND ONLY A 10 PERCENT
         CHANCE THAT IT WILL RISE ABOVE 12.9 FEET.


                    JAMES AND MISSOURI RIVER BASINS
                    LONG-RANGE PROBABILISTIC OUTLOOK
           PROBABILITIES FOR EXCEEDING LISTED RIVER STAGES
                                 FROM
TABLE 2

LOCATION              95%    90%    75%    50%    25%    10%    05%
--------            ------ ------ ------ ------ ------ ------ ------
LITTLE MUDDY CREEK.....
  WILLISTON            5.0    5.0    5.0    5.0   11.3   12.9   13.9
LITTLE MISSOURI RIVER.....
  MARMARTH             2.8    2.8    2.8    2.8    3.6    8.4    9.6
  MEDORA               2.9    2.9    2.9    3.3    4.4    9.2   10.2
  WATFORD CITY         0.3    0.3    0.5    2.2    5.0    6.5    7.2
KNIFE RIVER.....
  MANNING              6.4    6.4    7.0    8.9   10.4   14.2   16.1
SPRING CREEK.....
  ZAP                  5.2    5.2    5.8    9.2   10.8   18.1   19.0
KNIFE RIVER.....
  HAZEN                2.0    2.3    4.7   10.5   14.2   18.6   20.9
HEART RIVER.....
  MANDAN               1.3    1.3    2.0    4.1    6.4    7.0   18.3
APPLE CREEK.....
  MENOKEN              5.2    5.2    5.4   11.9   16.5   17.7   20.4
CANNONBALL RIVER.....
  REGENT               1.9    2.0    3.7    6.2    7.9    9.3   11.1
CEDAR CREEK.....
  RALEIGH              1.2    1.6    2.8    3.5    4.5    5.1    5.5
CANNONBALL RIVER.....
  BREIEN               4.3    4.4    5.9    7.1    7.8    9.7   10.2
BEAVER CREEK.....
  LINTON               5.2    5.2    5.8    7.9   11.1   13.2   18.1
JAMES RIVER.....
  GRACE CITY           5.2    5.2    5.2    5.4    6.5    7.7   11.3
PIPESTEM CREEK.....
  PINGREE              4.9    4.9    4.9    5.1    5.8    7.2    9.8
JAMES RIVER.....
  LAMOURE              8.6    8.6    8.6    8.7    9.2   15.2   17.1


...THE OUTLOOK PRODUCTION PROCESS...

THIS LONG RANGE PROBABILISTIC OUTLOOK IS BASED ON A SERIES OF PEAK
RIVER LEVELS OR CRESTS TAKEN FROM THE FORECAST HYDROGRAPH RESULTS
OF THE NWS ENSEMBLE STREAMFLOW PREDICTION MODEL (ESP). THE MODEL
IS RUN FOR MULTIPLE SCENARIOS STARTING AT CURRENT RIVER...SNOW AND
SOIL CONDITIONS AND USING 25 OR MORE YEARS OF PAST PRECIPITATION AND
TEMPERATURE CONDITIONS IN THE HISTORICAL RECORD. THESE CRESTS CAN
THEN BE RANKED FROM LOWEST TO HIGHEST...AND ASSIGNED AN
EXCEEDANCE PROBABILITY. FOR EXAMPLE...FOR A SERIES OF 50 YEARS...
THE LOWEST RANKED CREST HAS 49 CRESTS ABOVE IT AND SINCE 95 PERCENT
OF THE CRESTS ARE ABOVE IT... IT IS ASSIGNED A 95 PERCENT
PROBABILITY OF EXCEEDANCE (POE).

THE PROBABILITIES CAN BE USED FOR RISK MANAGEMENT BY COMPARING THIS
YEARS CURRENT TEMPERATURE AND PRECIPITATION OUTLOOKS WITH
THOSE OF PAST YEARS USED IN THE HYDRO OUTLOOK. THEY CAN ALSO BE
USED AS AN INDICATION OF THE RANGE OF CRESTS THAT MAY BE EXPECTED
DURING THE VALID PERIOD OF THE OUTLOOK.

BY PROVIDING A RANGE OF PEAK RIVER LEVEL PROBABILITIES..THE NWS IS
IS CONTRIBUTING TO THE AREAS DECISION SUPPORT SERVICES THAT HELP
WITH LONG RANGE FLOOD PLANNING AND RESPONSE READINESS.  THIS OUTLOOK
IS A PART OF NOAA/S NATIONAL WEATHER SERVICE/S AHPS (ADVANCED
HYDROLOGIC PREDICTION SERVICES).

THIS OUTLOOK WAS PRODUCED USING PRECIPITATION AND TEMPERATURES
FOR THE YEARS 1978 THROUGH 2002.

. ADDITIONAL INFORMATION SOURCES...

THE AHPS LONG RANGE PROBABILISTIC HYDROLOGIC OUTLOOKS ARE ISSUED
NEAR THE END OF EACH MONTH. HOWEVER...SPRING FLOOD AND WATER
RESOURCES OUTLOOKS ARE ISSUED SEVERAL TIMES DURING THE CRITICAL
SPRING MELT PERIOD...USUALLY ON THURSDAYS BEGINNING IN LATE
FEBRUARY OR EARLY MARCH AND ENDING IN EARLY APRIL...DEPENDING ON
THE SPRING FLOODING CONDITIONS.

THIS OUTLOOK IS ALSO PRESENTED AS GRAPHS OF THE PROBABILITY OF STAGE
EXCEEDANCE FOR THE FULL PERIOD AND FOR WEEKLY INTERVALS DURING THE
PERIOD. THESE GRAPHS...TOGETHER WITH EXPLANATIONS THAT HELP IN
INTERPRETING THEM ARE AVAILABLE FROM THE NWS BISMARCK AHPS WEB
PAGE ON THE INTERNET AT:

        WWW.WEATHER.GOV/BISMARCK OR WEATHER.GOV/BIS

    THEN CLICK ON THE "RIVERS AND LAKES AHPS"ON THE TAB ABOVE THE MAP
  ...OR ON THE LINK IN THE BLUE-LEFT-HAND BANNER.

CURRENT RIVER CONDITIONS FOR ALL FORECAST POINTS WITHIN THE SOURIS
RIVER BASIN ARE AVAILABLE ON OUR WEB SITE...AS WELL AS THE FORECASTS
WHEN THE RIVER AT THE FORECAST POINT IS IN OR NEAR FLOOD.

IF YOU HAVE ANY QUESTIONS...CONTACT THE NWS AT 701-250-4495.

PROBABILISTIC HYDROLOGIC OUTLOOKS WILL BE ISSUED MONTHLY THROUGHOUT
THE REST OF THE YEAR DURING THE LATER PART OF THE MONTH OR AS
CONDITIONS WARRANT.


$$
AJS
USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.